/*
 * Copyright 2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import * as React from "react";
import {UIEvent, UIEventHandler} from "react";

class ScrollObject {

    private handlers = new Set<UIEventHandler<HTMLElement>>();

    public addScrollEventListener(handler: UIEventHandler<HTMLElement>) {

        this.handlers.add(handler)
    }

    // public removeScrollEventListener(handler: UIEventHandler<HTMLElement>) {
    //     this.handlers.delete(handler)
    // }

    public handleScroll(e: UIEvent<HTMLElement>) {
        this.handlers.forEach(fn => fn(e));
    }

}

interface ScrollProps extends React.HTMLAttributes<HTMLDivElement> {

}

export default class Scroll extends React.Component<ScrollProps> {

    public static Context = React.createContext({});

    private scrollObject = new ScrollObject();

    public render() {
        const {...restProps} = this.props;
        return (
            <Scroll.Context.Provider value={this.scrollObject}>
                <div {...restProps} onScroll={this.scrollObject.handleScroll.bind(this.scrollObject)}>
                    {this.props.children}
                </div>
            </Scroll.Context.Provider>
        );
    }
}
